Modified uiO-66 material with vocs inhibition and self-healing function and preparation method

Abstract

The application belongs to the field of road engineering materials and environmental functional materials, and particularly relates to a modified UiO-66 material with VOCs inhibition and self-healing functions and a preparation method, which is obtained by introducing a self-healing functional group containing a reversible chemical bond or a hydrogen bond into an organic ligand or a surface of UiO-66, and the self-healing functional group contains at least one of a disulfide bond, a borate ester bond, an amino group, a carboxyl group, an ester group, a polyurethane segment or a Diels-Alder bond structure. The modified UiO-66 material has a porous structure and a high specific surface area, so that the modified UiO-66 material has a strong adsorption capacity for VOCs in asphalt, can significantly reduce the emission of VOCs, and reduces the harm to the environment and human health; the introduced dynamic chemical bond endows the material with a self-healing property, effectively improves the self-healing capacity of asphalt, prolongs the service life of the asphalt pavement, reduces the road maintenance cost, and has a significant economic value.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials and environmental functional materials, and specifically relates to a modified UiO-66 material with VOCs inhibition and self-healing functions and its preparation method. Background Technology

[0002] Asphalt is the main binder in road construction, but it releases a large amount of volatile organic compounds (VOCs) during production, transportation, construction, and service. These VOCs contain harmful components such as benzene compounds, ketones, and halogenated hydrocarbons, posing a serious threat to the environment and human health. Existing VOCs control methods mainly include adsorbents such as activated carbon and zeolite, but they suffer from poor adsorption selectivity and low adsorption efficiency, making it difficult to meet practical engineering needs. Metal-organic frameworks (MOFs) are considered a new generation of VOCs adsorption materials due to their high specific surface area, tunable pore size, and good thermal stability. UiO-66, as a typical zirconium-based MOF, can effectively adsorb VOCs in asphalt applications.

[0003] However, asphalt pavements are subject to the combined effects of vehicle loads, temperature cycling, and ultraviolet radiation during long-term service, making them highly susceptible to cracking and damage. Existing UiO-66 materials lack the ability to improve the structural performance of asphalt. Therefore, there is an urgent need for a novel modified material that combines VOCs suppression and self-healing properties to enhance the environmental friendliness and durability of asphalt materials. Summary of the Invention

[0004] To address the problems of insufficient VOCs suppression performance and poor self-healing ability of asphalt cracks in existing UiO-66 materials, this invention provides a modified UiO-66 material and its preparation method that combine VOCs suppression and self-healing properties. Specifically, the technical solution adopted is as follows: a modified UiO-66 material with VOCs suppression and self-healing functions, the structural formula of which is shown below:

[0005]

[0006] The R group is a self-healing functional group with dynamic chemical bonds, reversible bonds, or hydrogen bonds, and the R group contains at least one of the following structures: disulfide bond, borate ester bond, amino group, carboxyl group, ester group, polyurethane segment, or Diels-Alder bond.

[0007] A composite asphalt containing the modified UiO-66 material, wherein the modified UiO-66 material accounts for 0.5 to 5 wt% of the asphalt.

[0008] A method for preparing a modified UiO-66 material includes the following steps:

[0009] Step 1. Select UiO-66 or synthesize UiO-66 using a solvothermal method; select a modified organic compound, wherein the modified organic compound contains dynamic chemical bonds or reversible bonds, or the modified organic compound is a self-healing functional monomer containing hydrogen bonds, Diels-Alder bonds or polyurethane segments.

[0010] Step 2. Prepare raw materials according to a mass ratio of UiO-66:modified organic compound of 2~3:1;

[0011] Step 3. Dissolve the modified organic compound in toluene and stir to form a uniform modified liquid. Slowly add the UiO-66 material to the modified liquid and disperse it using an ultrasonic disperser to form a mixture. Transfer the uniformly dispersed mixture to a three-necked flask, install a nitrogen inlet tube, a condenser and a stirring device. First, purge the air in the flask to form an inert reaction atmosphere, and carry out the grafting reaction in a constant temperature water bath with magnetic stirring.

[0012] Step 4. After the reaction is complete, transfer the cooled mixture to a centrifuge tube and centrifuge. Wash with toluene and methanol in sequence to remove residues. Place the washed precipitate in a vacuum drying oven and dry it at 60~70℃ and -0.09MPa for 8~9h to obtain powdered modified UiO-66 material.

[0013] Furthermore, the modified organic compound containing dynamic chemical bonds or reversible bonds in step 1 is dimethyl dithiodipropionate containing disulfide bonds or organic compounds containing borate ester bonds.

[0014] Furthermore, the solvothermal synthesis of UiO-66 in step 1 is as follows: soluble zirconium salt and terephthalic acid are dissolved in a polar amide solvent (such as N,N-dimethylformamide, DMF, purity ≥99.5wt%), and stirred until homogeneous at 80-120℃ to form a transparent solution. This solution is then transferred to a reaction vessel and subjected to a hydrothermal reaction at 120-180℃ for 12-24 hours. After the reaction, the mixture is naturally cooled to room temperature, and the precipitate is obtained by centrifugation. Impurities are removed by repeated washing with DMF and methanol, and finally, the mixture is vacuum dried at 60-80℃ to obtain the UiO-66 material.

[0015] Furthermore, when dimethyl dithiodipropionate is selected as the modified organic compound in step 3, the temperature of the constant temperature water bath is set to 50~60℃ and the reaction time is 6~8h.

[0016] Furthermore, when selecting organic compounds containing borate ester bonds as the modified organic compounds in step 3, the temperature of the constant temperature water bath is set to 60~80℃, and the reaction time is 8~12h.

[0017] Furthermore, during the reaction process in step 3, samples were taken every 1 to 1.5 hours, and the dispersion state of UiO-66 was observed under a microscope. When agglomeration occurred, ultrasonic dispersion treatment was performed to ensure that the grafting reaction proceeded uniformly.

[0018] Compared with existing technologies, the beneficial effects of this technical solution are as follows:

[0019] 1. A modified UiO-66 material with VOCs inhibition and self-healing functions is provided. Its porous structure and high specific surface area enable it to have a strong adsorption capacity for VOCs in asphalt, which can significantly reduce VOCs emissions, reduce the harm to the environment and human health, and the introduced dynamic chemical bonds endow the material with self-healing properties, effectively improve the self-healing ability of asphalt, extend the service life of asphalt pavement, and reduce road maintenance costs.

[0020] 2. A method for preparing modified UiO-66 is provided. The process is simple and can be mass-produced and applied. The modification process of this preparation method is carried out without destroying the stability of the original framework structure of UiO-66, which ensures the long-term effectiveness of the material in the complex environment of asphalt, can improve the service life of road materials, and has significant economic value. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the adsorption of VOCs and self-healing mechanism of cracks in composite asphalt prepared using the modified UiO-66 material provided by this invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. However, the scope of the present invention is not limited to the following embodiments.

[0023] Example 1

[0024] A method for preparing a modified UiO-66 material includes the following steps:

[0025] Step 1. Prepare raw materials: Accurately weigh 1.0g zirconium chloride (purity ≥99.0wt%) and 0.8g terephthalic acid (purity ≥98.0wt%). Prepare N,N-dimethylformamide (purity ≥99.5wt%), methanol (purity ≥99.5wt%), toluene (purity ≥99.0wt%), and dimethyl dithiodipropionate (an organic compound containing disulfide bonds, purity ≥98.0wt%), ensuring that all raw materials are free from impurities.

[0026] Step 2. Solvothermal synthesis of UiO-66: 1.0 g ZrCl4 was slowly added to 50 mL DMF and placed in a constant temperature water bath at 100 °C. The magnetic stirring speed was 300 r / min, and stirring was continued for 60 min until the ZrCl4 was completely dissolved, forming a clear and transparent solution. Subsequently, 0.8 g terephthalic acid was slowly added, maintaining a constant temperature of 100 °C and stirring at 300 r / min for 30 min. During this period, the solution state was observed to ensure that the terephthalic acid was completely dissolved and a homogeneous and stable mixed solution was formed. The above mixed solution was transferred to a 100 mL polytetrafluoroethylene-lined reactor, sealed, and placed in an oven at 150 °C for 18 h. During the reaction, the oven temperature was recorded every 3 h to ensure that the temperature fluctuation did not exceed ±2 °C and to ensure stable reaction conditions. After the reaction was completed, the oven was turned off, and the reactor was allowed to cool naturally to room temperature (approximately 25 °C). The liner was removed, and the solution was transferred to centrifuge tubes. A high-speed centrifuge was used, set to 8000 rpm for 15 minutes, and the bottom precipitate was collected. The precipitate was first washed three times with 50 mL of DMF, centrifuged at 8000 rpm for 15 minutes after each wash to remove unreacted ZrCl4 and terephthalic acid. Then, it was washed three times with 50 mL of methanol, again centrifuged for 15 minutes each time, to further remove residual impurities, finally obtaining a pure UiO-66 wet precipitate. The washed UiO-66 wet precipitate was placed in a vacuum drying oven, set to 70℃ and -0.09 MPa, and dried for 12 hours. During the drying process, the precipitate was observed every 2 hours to prevent clumping. After drying, a white powdery UiO-66 material was obtained, weighed, recorded, and used for later use.

[0027] Step 3. Weigh 0.5 g of the dried UiO-66 material and disperse it in 50 mL of toluene solution containing 0.2 g of dimethyl dithiopropionate. Transfer the mixture to a three-necked flask and purge with nitrogen gas (purity ≥99.99%) at a flow rate of 50 mL / min to purge air from the flask. Continue purging with nitrogen gas for 30 min. Then, place the three-necked flask in a constant-temperature water bath at 60 °C with a magnetic stirring speed of 250 r / min for 8 h. During the reaction, take a small amount of solution every 1 h using a sampling tube to observe the dispersion state and ensure uniform reaction.

[0028] Step 4. After the reaction is complete, stop the nitrogen flow and transfer the mixture to a centrifuge tube. Centrifuge at 8000 rpm for 15 min and collect the precipitate. First, wash the precipitate three times with 50 mL of toluene, centrifuging for 15 min each time to remove unreacted dimethyl dithiodipropionate. Then, wash the precipitate three times with 50 mL of methanol, centrifuging for 15 min each time to remove residual toluene. Finally, place the precipitate in a vacuum drying oven and dry it at 60℃ and -0.09 MPa for 8 h to obtain a light yellow powdery modified UiO-66 material. Weigh and record the weight, then seal and store it.

[0029] The method for applying modified UiO-66 material to asphalt is as follows: Weigh 100g of base asphalt, heat it to 160℃ to make it flow, then add 0.5g of the modified UiO-66 material prepared above, and shear and stir at high speed at 4000rpm for 30 minutes to fully mix the material with the asphalt to obtain the desired composite asphalt material.

[0030] VOCs inhibition effect test: VOCs release was detected using gas chromatography-mass spectrometry (GC-MS). 20g of the prepared composite asphalt sample was placed in a heatable, sealed container and heated at 160℃ for 2 hours, during which the released gas was collected using a gas collection bag. GC-MS analysis showed that the total VOCs release from the composite asphalt was 286.3 mg / m³, while the total VOCs release from the blank base asphalt without modification was 440.5 mg / m³ under the same conditions, indicating a 35.0% reduction in VOCs release. Simultaneously, analysis of VOC components revealed a 32.5% reduction in aliphatic hydrocarbon concentration, a 38.2% reduction in aromatic hydrocarbon concentration, a 41.3% reduction in sulfur-containing compound concentration, and a 39.8% reduction in the concentration of Group 1 carcinogens (such as benzene and 1,3-butadiene).

[0031] Self-healing performance verification: The prepared composite asphalt was made into standard small beam specimens (25mm×25mm×100mm), and the self-healing performance was tested using a bending beam rheometer (BBR) and a dynamic shear rheometer (DSR). BBR test: A constant load was applied to the specimen at -10℃, and the initial stiffness modulus was recorded. The specimen was then cut to form a 0.5mm wide crack, cured at 60℃ for 2 hours, and the stiffness modulus was tested again to calculate the self-healing efficiency. The results showed that the self-healing efficiency of the composite asphalt was 48.2%, while that of the blank base asphalt was 26.0%, representing an improvement of 22.2%. DSR test: At 60℃ and 10rad / s, the complex shear modulus (G*) and phase angle (δ) of the composite asphalt were tested. After curing with the cut crack, the test was repeated, and the G* recovery rate was calculated. The G* recovery rate of the composite asphalt was 45.8%, while that of the blank base asphalt was 23.5%, further verifying the improved self-healing performance.

[0032] Figure 1 This is a schematic diagram of the adsorption of VOCs and the self-healing mechanism of cracks in the prepared composite asphalt.

[0033] Example 2

[0034] A method for preparing a modified UiO-66 material includes the following steps:

[0035] Step 1. Prepare raw materials: Accurately weigh 1.2g zirconium chloride (purity ≥99.0wt%), 0.9g terephthalic acid (purity ≥98.0wt%), and prepare 60mL of N,N-dimethylformamide (purity ≥99.5wt%), methanol (purity ≥99.5wt%), toluene (purity ≥99.0wt%), and boron ester bond organic compound (purity ≥97.0wt%), ensuring that all raw materials are free from impurities.

[0036] Step 2. Solvothermal synthesis of UiO-66: Add 1.2 g ZrCl4 to 60 mL of LDM, place in a constant temperature water bath at 80 °C, and stir magnetically at 280 r / min for 45 min until ZrCl4 is completely dissolved. Add 0.9 g terephthalic acid, maintain a constant temperature of 80 °C, and stir at 280 r / min for 40 min to form a homogeneous mixture. Observe every 10 min during this period to ensure no solid particles remain. Transfer the mixture to a 100 mL PTFE-lined reactor, seal it, and place it in an oven at 160 °C for 20 h. Record the temperature every 4 h during the reaction, controlling the temperature fluctuation within ±1 °C. After the reaction, cool to room temperature, transfer the solution to centrifuge tubes, centrifuge at 8000 r / min for 15 min, and collect the precipitate. Wash three times with 60 mL DMF, centrifuging for 15 min each time; then wash three times with 60 mL methanol, centrifuging for 15 min each time, to obtain a wet precipitate of UiO-66. Place the wet precipitate in a vacuum drying oven and dry at 70 °C and -0.09 MPa for 14 h to obtain a white powdery UiO-66 material, which is weighed, recorded, and set aside for later use.

[0037] Step 3. Weigh 0.6g of UiO-66 material and disperse it in 60mL of toluene solution containing 0.25g of borate ester bond organic compound. Transfer the solution to a three-necked flask and purge with nitrogen gas (50mL / min) for 30min to remove air. Set the water bath temperature to 70℃ and the magnetic stirring speed to 260r / min. React for 10h, taking samples every 1.5h to observe the dispersion state and ensure uniform reaction.

[0038] Step 4. After the reaction is complete, centrifuge at 8000 r / min for 15 min and collect the precipitate. Wash with 60 mL of toluene three times and centrifuge, then wash with 60 mL of methanol three times and centrifuge. Finally, dry under vacuum at 60℃ and -0.09 MPa for 9 h to obtain the modified UiO-66 material. Weigh and record the weight, then seal and store.

[0039] The method for applying modified UiO-66 material to asphalt is as follows: Weigh 120g of base asphalt, heat it to 170℃ to make it flow, then add 1.0g of the modified UiO-66 material prepared above, and shear and stir at high speed at 5000rpm for 25 minutes to fully mix the material with the asphalt to obtain the desired composite asphalt material.

[0040] VOCs inhibition effect test: VOCs release was detected by gas chromatography-mass spectrometry (GC-MS). A 25g sample of composite asphalt was placed in a sealed container and heated at 170℃ for 2 hours. The gas was collected using a gas collection bag and analyzed by GC-MS. The results showed that the total VOCs release from the composite asphalt was 252.1 mg / m³, while that from the blank matrix asphalt was 434.7 mg / m³, representing a 42.0% reduction in VOCs release. Specifically, the concentrations of aliphatic hydrocarbons decreased by 39.8%, aromatic hydrocarbons by 45.2%, sulfur compounds by 48.5%, and the total concentration of Group 1 carcinogens by 46.3%.

[0041] Self-healing performance verification: The prepared composite asphalt was made into standard small beam specimens (25mm×25mm×100mm), and the self-healing performance was tested using a bending beam rheometer (BBR) and a dynamic shear rheometer (DSR). BBR test: A constant load was applied to the specimen at -10℃, and the initial stiffness modulus was recorded; a 0.5mm crack was cut, and the specimen was cured at 60℃ for 2 hours, followed by a second test. The self-healing efficiency of the composite asphalt was 52.3%, while that of the blank base asphalt was 26.1%, representing an improvement of 26.2%. DSR test: Under conditions of 60℃ and 10rad / s, the G* recovery rate of the composite asphalt was 50.1%, while that of the blank base asphalt was 24.0%, further demonstrating the improved self-healing performance.

[0042] Comparative Example 1

[0043] UiO-66 material was prepared according to steps 1 and 2 of Example 1, but without subsequent modification steps, resulting in unmodified UiO-66 material.

[0044] Weigh 100g of base asphalt, heat it to 160℃ to make it flow, then add 0.5g of the above unmodified UiO-66 material, and shear and stir at high speed at 4000rpm for 30 minutes to fully mix the material with the asphalt to obtain unmodified UiO-66 composite asphalt.

[0045] VOCs release was detected using gas chromatography-mass spectrometry (GC-MS): Following the same method as in Example 1, 20g of unmodified UiO-66 composite asphalt was heated at 160℃ for 2 hours, followed by GC-MS detection. The total VOCs release from the unmodified UiO-66 composite asphalt was 286.5 mg / m³, while that from the blank matrix asphalt was 440.5 mg / m³, representing a 35.0% reduction in VOCs release. This is similar to the VOCs inhibition effect of the modified UiO-66 in Example 1. However, component analysis showed that its inhibition rates against aromatic hydrocarbons and Group 1 carcinogens (32.1% and 33.5%, respectively) were lower than those in Example 1 (38.2% and 39.8%, respectively).

[0046] The self-healing performance was tested using a bending beam rheometer (BBR) and a dynamic shear rheometer (DSR). Similar to the method used in Example 1, the BBR test showed that the self-healing efficiency of the unmodified UiO-66 composite asphalt was 25.8%, essentially the same as that of the blank base asphalt (26.0%). The DSR test showed a G* recovery rate of 24.2%, with minimal difference from the blank base asphalt (23.5%), indicating that the unmodified UiO-66 had no significant effect on improving the self-healing performance of asphalt.

Claims

1. A modified UiO-66 material with VOCs inhibition and self-healing functions, characterized in that... The structural formula is: The R group is a self-healing functional group with dynamic chemical bonds, reversible bonds, or hydrogen bonds, and the R group contains at least one of the following structures: disulfide bond, borate ester bond, amino group, carboxyl group, ester group, polyurethane segment, or Diels-Alder bond.

2. A composite asphalt containing the modified UiO-66 material as described in claim 1, characterized in that: The modified UiO-66 material accounts for 0.5~5wt% of the asphalt.

3. A method for preparing the modified UiO-66 material according to claim 1, characterized in that, Includes the following steps: Step 1. Select UiO-66 or synthesize UiO-66 using a solvothermal method; select a modified organic compound, wherein the modified organic compound contains dynamic chemical bonds or reversible bonds, or the modified organic compound is a self-healing functional monomer containing hydrogen bonds, Diels-Alder bonds or polyurethane segments. Step 2. Prepare raw materials according to a mass ratio of UiO-66:modified organic compound of 2~3:1; Step 3. Dissolve the modified organic compound in toluene and stir to form a uniform modified liquid. Slowly add the UiO-66 material to the modified liquid and disperse it using an ultrasonic disperser to form a mixture. Transfer the uniformly dispersed mixture to a three-necked flask, install a nitrogen inlet tube, a condenser and a stirring device. First, purge the air in the flask to form an inert reaction atmosphere, and carry out the grafting reaction in a constant temperature water bath with magnetic stirring. Step 4. After the reaction is complete, transfer the cooled mixture to a centrifuge tube and centrifuge. Wash with toluene and methanol in sequence to remove residues. Place the washed precipitate in a vacuum drying oven and dry it at 60~70℃ and -0.09MPa for 8~9h to obtain powdered modified UiO-66 material.

4. The preparation method according to claim 3, characterized in that: The modified organic compound containing dynamic chemical bonds or reversible bonds in step 1 is dimethyl dithiodipropionate containing disulfide bonds or organic compounds containing borate ester bonds.

5. The preparation method according to claim 4, characterized in that: In step 3, when dimethyl dithiodipropionate is selected as the modified organic compound, the temperature of the constant temperature water bath is set to 50~60℃ and the reaction time is 6~8h.

6. The preparation method according to claim 4, characterized in that: In step 3, when selecting organic compounds containing borate ester bonds for modification, the temperature of the constant temperature water bath is set to 60~80℃, and the reaction time is 8~12h.

7. The preparation method according to claim 3, characterized in that: During the reaction in step 3, samples were taken every 1 to 1.5 hours, and the dispersion state of UiO-66 was observed under a microscope. When agglomeration occurred, ultrasonic dispersion was performed to ensure that the grafting reaction proceeded uniformly.

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